The present invention relates to a base-bleed gas generator for the rear part of a projectile, shell or the like.
It is previously known to increase the range of, for instance, artillery projectiles by reducing the base drag of the projectile by means of a suitable base flow, that is to say a combustion gas is ejected from the base surface of the projectile. This has the effect that the low-pressure area behind the projectile is filled up by the gases and the base drag is reduced. In contrast to a reatile, the gas flow velocity is very low and the base flow should occur during a substantial part of the flight time of the projectile.
In order to utilize this base-bleed effect, it is previously known to provide the rear part of the projectile with a tubular base-bleed housing comprising a combustion chamber containing an annularly shaped propellant having a comparatively low burning rate, and a central, comparatively large discharge aperture in the base wall of the combustion chamber for the combustion gases. The base-bleed propellant is preferably a composite propellant composed of polybutadiene as binder (fuel) and ammonium perchlorate as an oxidant.
The base-bleed propellant is ignited by the hot combustion gases generated in the gun tube on the launching of the projectile or the like and flowing into the combustion chamber. The propellant may be extinguished, however, due to the steep pressure drop in the combustion chamber when the projectile leaves the muzzle. For this reason an igniter is usually arranged in the gas generator to prevent such extinguishment during the pressure drop in the combustion chamber.